Crude oils containing nitrogen dispersants and alkoxylated ashless surfactants usable as diesel fuels

ABSTRACT

Synthetic or natural crude oils having low inorganic salt and sulfur contents and which contain a polymeric dispersant and an alkoxylated ashless surfactant are useful as fuels for heavy duty diesel engines. The ashless dispersants of this invention can be characterized as having long carbon chains joined to a polar oxygen-containing or nitrogen-containing moiety. The surface active agents of this invention have a polar moiety such as an acidic or phenolic group alkoxylated with an alkylene oxide. The crude oils used in this invention have a sulfur content of 1 wt. % or less and an inorganic salt content below 3 pounds per thousand barrels of crude oil. The crude oil can be of paraffinic, asphaltic or a mixed type or a synthetic crude isolated from oil or tar sands.

United States Patent Steere et CRUDE OILS CONTAINING NITROGEN DIESELFUELS [75] Inventors: David E. Steere, Sarnia, Canada; Thorkild F.Lonstrup, Goring on Thames, England [73] Assignec: Exxon Research &Engineering Co.,

Linden, NJ

[22] Filed: Oct. 27, 1972 [21] Appl. No.: 301,612

[52] US. Cl. 44/66; 44/71; 44/72 [51} Int. Cl. ClOL l/24 [58] Field ofSearch 44/66. 71, 72; 252/DIG. 1, 252/351, 353

[56] References Cited UNITED STATES PATENTS 3,219.666 11/1965 Norman etal 252/515 A $367,943 2/1968 Miller et al. 44/71 3,381,022 4/1968 LeSuer260/404.8 1630.953 12/197] Simon et a] 252/351 3.658.495 4/1972 Dorer.Jr. 44/71 3,658.707 4/1972 Delafield et al. 44/71 1451 Nov. 18, 1975FOREIGN PATENTS OR APPLICATIONS 830,864 3/1960 United Kingdom 252/1310.1

Primary Examiner-Daniel E. Wyman Assistant ExaminerY. Harris SmithAttorney, Agent, or Firm-Daniel H. Hall; Byron O Dimmick ABSIRACTSynthetic or natural crude oils having low inorganic salt and sulfurcontents and which contain a polymeric dispersant and an alkoxylatedashless surfactant are useful as fuels for heavy duty diesel engines.The ash less dispersants of this invention can be characterized ashaving long carbon chains joined to a polar oxygencontaining ornitrogen-containing moiety. The surface active agents of this inventionhave a polar moiety such as an acidic or phenolic group alkoxylated withan alkylene oxide. The crude oils used in this invention have a sulfurcontent of 1 wt. or less and an inorganic salt content below 3 poundsper thousand barrels of crude oil. The crude oil can be of paraffinic,asphaltic or a mixed type or a synthetic crude isolated from oil or tarsands.

7 Claims, No Drawings CRUDE OILS CONTAINING NITROGEN DISPERSANTS ANDALKOXYLATED ASHLESS SURFACTANTS USABLE AS DIESEL FUELS FIELD OF THEINVENTION This invention relates to crude oil compositions of low sulfurand inorganic salt content containing a dispersant and a surfactantadditive, both of which are H 1 DESCRIPTION OF THE PRIOR ART Recently,it was discovered that naturally occurring or synthetic crude oilscontaining low sulfur and inorganic salt contents can be made usable asfuels for diesel engines by the addition to them of a dispersantselected from the group consisting of overbased alkaline earth metalsulfonates and alkylene polyamine condensation products such as some ofthe dispersants of the present invention. This invention was disclosedin U.S. Pat. No. 3,594,137.

The present invention represents an improvement over that invention inthat it has now been found that it is possible to omit any ash-formingmaterial from the crude oil and still obtain a fuel useful for operationof a diesel engine.

The above-noted U.S. Pat. No. 3,594,137 taught that the best results areobtained by using a combination of an ash'forming sulfonate with anashless dispersant. It has now been found that the combination of anashless dispersant with an ashless alkoxylated surfactant is similarlyeffective. Furthermore, the combination of the present invention, beingtotally ashless, contributes no solid particles to the environment uponcombustion.

SUMMARY OF THE INVENTION It has now been found that crude oils of lowsulfur and inorganic salt content can be made into fuels for dieselengines by combining them with an ashless dispersant and an ashlessalkoxylated surfactant. The dispersants of the present invention havelong hydrocarbon chains attached to a polar moiety and the ashlesssurfactants of the present invention are the reaction products of analkylene oxide with an acidic organic material such as a carboxylicacid, an alkyl phenol or a hydrocarbon sulfonic acid.

Attempts have been made in the past to employ crude oils as fuels forcompression engines such as heavy duty diesel engines. The incentive forsuch attempts has been one of economy. Unfortunately, such attempts inthe past have shown poor results because of the resulting corrosionproblems and the formation of high carbonaceous deposits in the engines.These deposits adversely affect the operation of the fuel injectors andlead to excessive fuel consumption. In addition. the attempted use ofsuch crude oils as diesel fuels gave a diesel lubricating oil usefullife of the order of 10,000 miles when used in a railroad diesel enginevs. an oil life in excess of 50,000 miles when conventional diesel fuelwas used.

The principal reason for this short life of the diesel lubricating oilwas that excessive sludge and soot deposits accumulated in the oil.These deposits were not removed by the customary oil filters used inconnection with the operation of heavy duty diesel engines.

It was subsequently discovered that the principal reason for theexcessive corrosion and carbon deposition pertaining to the fuelinjectors and lack of general engine cleanliness was that the crude oilsemployed contained excessive amounts of inorganic salts, elementalsulfur and sulfur compounds which are naturally occurring in many crudeoils. The effective removal of excessive inorganic salts from crude oilsis a conventional process which has been practiced for many years and itwas discovered that where the natural or synthetic crude oils containedmore than about three pounds of inorganic salts per thousand barrels ofoil, it was necessary to process such oils to bring the amount ofinorganic salts below this figure in order for the crude oils to besatisfactorily employed as diesel fuels. The desalting techniques foraccomplishing this are well known. See, for example, U.S. Pat. Nos.2,074,183 and 2,l40,574. Essentially in these processes, crude oil isdesalted by adding limited amounts of water to the crude, heating thecrude oil under pressure to avoid loss of low boiling constituents,gently stirring the same to avoid emulsion formation and allowing thesalts to settle. Decantation, centrifugation or filtering may then beemployed to separate the salts from the crude oil and, of course, theremaining water containing the dissolved salts is separated inconventional manner, as, for example, by further settling anddecantation. In general, the desalting operation involves washing thesalts from the oil under such conditions that rapid separation of thewater solution from the oil together with undissolved inorganic salts,as solids, can be effectively carried out.

It was also discovered that excessive amounts of sulfur and sulfurcompounds, again naturally occurring in many crude oils as producedthroughout the world, caused deleterious effects in the operation andmaintenance of heavy duty diesel engines. It was, therefore, foundnecessary in order to successfully use desalted natural and syntheticcrude oils as diesel fuels to additionally desulfurize or sweeten themto the point where the sulfur content, both free and chemicallycombined, was less than l.0 wt. 7r. Here again, processes for sweeteningor desulfurizing oils are conventional and have been known for manyyears. Representative U.S. patents showing such processes are U.S. Pat.Nos. 607,017; 620,882; 1,654,58l and 1,608,339. The conventionaldesalting and sweetening operations form no part of the presentinvention.

British Pat. No. 1,124,611 discloses a conventional diesel fuelcontaining an ashless dispersant and an alkyl nitrate. Such conventionalfuels are more highly refined and accordingly more expensive than thecrude oil fuels of the present invention.

DETAILED DESCRIPTION OF THE INVENTION Crude Oils The crude oils whichcan be used in the practice of the present invention constitute alltypes of crude oils produced throughout the world. They can be ofparaffinic, asphaltic or mixed types. They can be naturally occurringcrude oils or those which have been isolated from oil sands and shaleoil deposits. It is preferred, however, to use naturally occurring orsynthetic crude oils derived from oil sands.

It has been found that crude oils containing appreciable amounts ofaromatic constituents, and to some extent crude oils containingappreciable amounts of naphthenic constituents are less desirable thanare the paraffinic, mixed crudes and asphaltic crudes. In general, thecrude oils, treated or untreated, which meet the above-defined sulfurand salt specifications are suitable for direct use in undiluted orunaltered form if they have an API gravity of between about 25 and about45 measured at 60F and if they have a viscosity of between about 35 and250 SUS at l"F. In using the higher viscosity oils. preheating of theoil is oftentimes employed to lower its viscosity for ease of injection.

in general, these crudes will have atmospheric pressure equivalentdistillation boiling ranges between about 160 and about l.lO0F. Manycrudes will have far narrower boiling ranges, particularly the syntheticcrude oils, a typical one having a final distillation end point of below700F. Conventional diesel fuels have a distillation range between about350 and about 650F, but naturally the crude oils will have appreciableamounts of components boiling below 350 and above 650F. This does notadversely affect the operation of diesel engines.

Typical specific crudes which may be employed are desalted Pembina crudefrom Canada and synthetic crude prepared from Athabasca tar sands ofCanada, wherein a hydrogenation of the virgin and delayed coker gas oilsis carried out. This last named material is light in color and resemblesa distillate fuel and is only slightly higher in its final boiling pointthan that of conventional diesel fuels although it contains anappreciable front end fraction with an initial boiling point slightlyhigher than that of conventional diesel fuel. Another synthetic typecrude oil is that obtained and recovered from the distillation ofoilcontaining shales. A representative material has an initial boilingpoint of about 430F and a final boiling point of about l,050F, an APIgravity of l9 at 60F and a viscosity of 200 SUS at 100F. Other specifictypes of crudes which are advantageously employed include those from theLeduc field in Western Canada, the paraffinie crudes of Pennsylvania andthe Middle East, the mixed base crude oils of the Mid Continent and theasphalt base crudes of the Gulf Coast and California.

The desalted and sweetened crude oils discussed above were tried asfuels for marine and railroad heavy duty diesel engines without anyfurther treatments but they did not perform well. It was found thatdespite these pretreatments, unsatisfactory diesel lubricating oil liferesulted and heavy fouling of the fuel injectors occurred. In theseearlier tests in laboratory engines, it was necessary to change fuelinjectors about every hours in order to avoid excessive injectorfouling. The used oil life was relatively short. Heavy sludge and fuelsoot were deposited in the lubricating oil. Additionally. the used oilclearly showed the result of the injector fouling because it had as muchas 41% viscosity increase coupled with the aforementioned additionaldisadvantages.

It was found that a more successful operation of these heavy duty dieselengines. from an overall performance standpoint, could be accomplishedif the injectors could be maintained relatively clear and free ofcarbonaceous deposits and ifthey could, of course, be free of injectorcorrosion. Surprisingly. the incorporation into the crude oil dieselfuel of relatively small amounts of either an ashforming dispersant oran ashless dispersant. or preferably both types, gave a surprisingeffect as to reduced fuel consumption, piston cleanliness, improvedlubricating oil life and injector cleanliness. The overall freedom fromcomplications in the operation and maintenance of heavy duty dieselengines using these additive-treated fuels was comparable to thatattainable using conventional and regular diesel fuel. Similarimprovements have now been realized using the totally ashless additivecombination of the present invention at lesser concentrations than theaforementioned ash-containing additive combination. Dispersant AdditivesThe dispersant additives of the present invention are characterized byhaving a long hydrocarbon chain, typically containing 40 to 250 carbonatoms per chain, attached to a polar organic moiety. These materials areashless and sold commercially on the open market, principally asdispersants for automotive lubricating oils. Typical patents whichdisclose their preparation and use are US. Pat. Nos. 3,172,892 and3,219,666.

A particularly useful class of dispersants for the present invention arethose which contain nitrogen. These dispersants includemineral-oil-soluble salts, amides, imides and esters of monoanddiearboxylic acids (and, where they exist, the corresponding acidanhydrides) and various amines or nitrogen-containing materials havingamino nitrogen or heterocyclic nitrogen and at least one amido orhydroxy group capable of salt, amide, imide or ester formation. Thediacids and anhydrides are preferably alkenyl substituted. Thesedispersants are characterized by a long chain hydrocarbon group orgroups attached to the acid so that the acid contains a total of about50 to 250 carbon atoms, said acid being attached to the amine eitherthrough salt. imide, amide or ester groups. Usually, these dispersantsare made by condensing a monocarboxylic acid or a dicarboxylic acid,preferably a succinic acid producing material such as alkenyl succinicanhydride, with an amine or polyamine.

Monocarboxylic acid dispersants have been described in British PatentSpecification No. 983,040. There, the high molecular weightmonocarboxylic acids were derived from a polyolefin, such aspolyisobutylene, by oxidation with nitric acid or oxygen, or by additionof halogen to the polyolefin followed by hydrolysis and oxidation. Themonocarboxylic acid may also be obtained by oxidizing a monohydricalcohol with potassium permanganate or by reacting a halogenatedpolyolefin with a ketone.

Another method is taught in Belgian Pat. No. 658.236 where polymers of Cto C monoolefins, e.g. polypropylene or polyisobutylene, arehalogenated, e.g. chlorinated, and then condensed with an alpha.beta-unsaturated monocarboxylic acid of from 3 to 8, preferably 3 to 4,carbon atoms. e.g. acrylic acid. alpha-methacrylic acid, crotonic acid.or isocrotonic acid, tiglic acid (alpha-methylcrotonic acid), angelicacid (alpha-methylisocrotonic acid), sorbic acid, cinnamic acid, etc.Esters of such acids, e.g. ethyl methacrylate, may be employed ifdesired in place of the free acid.

The most commonly used dicarboxylic acid is alkenyl succinic anhydridewherein the alkenyl group contains about 60 to 250 carbon atoms.

Primarily because of its ready availability and low cost, thehydrocarbon portion of the monoor dicarboxylic acid is preferablyderived from a polymer of a C to C monoolefin, said polymer generallyhaving a molecular weight of about 700 to 3.000, e.g. about 700 to1,300. Particularly preferred is polyisobutylene.

Polyalkyleneamines are usually the amines used to make the dispersant.These polyalkylencamines include those represented by the generalformula H,N(CH,).,-INH(CH,),,l,,,-NH(CH,1,,NH wherein n is 2 or 3, and mis to l0. Examples of such polyalkyleneamines include diethylenetriaminc, tetraethylene pentamine, oetaethylene nonamine, tetrapropylenepentamine, as well as various cyclic polyalkyleneamines. Mixtures ofthese amines can also be used.

Dispersants formed by reacting about equal molar amounts ofpolyisobutenyl succinic anhydride and a tetructhylenc pentamine aredescribed in U.S. Pat. No. 3,202,678.

Similar dispersants, but made by reacting a molar amount of alkenylsuccinic anhydride with about two molar amounts of alkenyl suceinicanhydride with about two molar amounts of polyalkyleneamincs, aredescribed in U.S. Pat. No. 3,154,560. Other dispersants, using stillother molar ratios of alkenyl suceinic anhydride and polyalkyleneaminesare described in U.S. Pat. No. 3,172,892. Still other dispersants ofalkenyl suceinic anhydride with other amines are described in U.S. Pat.Nos. 3,024,195 and 3,024,237 (piperazine amines); and 3,219,666. Anester derivative is taught in Belgian Pat. No. 662,875 where N-alkylmorpholinone esters, e.g. N-(Z-hydroxyethyl)-2-morpholinone, are formedby reaction with polyisobutylene succinic anhydride. The prior art alsoteaches that the alkenyl succinie polyamine type dispersants can befurther modified by reacting a fatty acid, having from 2 to 22 carbonatoms.

e.g. acetic acid, with the reaction product of the alkenyl succinicanhydride and polyamine (see U.S. Pat. No. 3,2l6,936).

For the purposes of the present invention any of the nitrogen-containingdispersants described in any of the aforementioned patents can be usedin carrying out the present invention.

Also useful as dispersants in the present invention are those materialswhich are made by condensation of the above-described organic acids witha polyol such as pentaerythritol, glycol, etc. Such dispersants aredescribed in U.S. Pat. Nos. 3,381,022, 3,522,179 and 3,542,678.

Ashless Alkoxylated Surfactants The ashless surfactants used in thepresent invention are generally made by the reaction of an alkyleneoxide such as ethylene or propylene oxide with an acidic organicmaterial. Among such acidic organic materials are fatty acids having 2to 30, preferably 8 to carbon atoms, phenols and alkylated phenolshaving 6 to 30, preferably 12 to 20 carbon atoms and synthetic and petroleum sulfonic acids having 2 to 30, preferably 8 to 20 carbon atoms.

The alkoxylated fatty-acid-derived surfactants used in the presentinvention have the general formula:

wherein R is a C to C preferably C to C,.,, aliphatic group. A is anoxygen or sulfur atom. n and m are each numbers from 0 to l4 and the sumofn m is between 2 and 14.

The above-noted alkoxylated organic acid materials generally containfrom 2 to 14 molar units derived from 6 an alkylene oxide, preferably 5to [2 molar units. Specific examples of the fatty acids used to make thesurfactants of this invention include the following:

Caprylic Stearie Capric Oleic Laurie [.inoleic Myristic GadoleiePalmitic Cetoleie. etc.

The phenols which can be condensed with the abovenoted aklylene oxidesto form the ashless surfactants of the present invention have thefollowing general formula:

wherein A is an oxygen or sulfur atom, preferably an oxygen atom; R is ahydrocarbyl group, preferably an aliphatic group, containing 1 to 20carbon atoms; most preferably R is an alkyl group containing 6 to 14carbon atoms. Among the alkyl groups which R can represent are thefollowing:

methyl n-propyl isobutyl tertiary butyl n-hexyl Z'ethyI hexyl n-dodecyliso-dodeeyl n-oetadecyl. etc.

The resultant alkoxylated phenols have the general formula:

HZI

wherein A and R' are as defined above, n and m are each numbers from Oto 14 and the sum of n' m' is between about 6 and [4.

Many of the above-described alkoxylated alkyl phenols and alkoxylatedfatty acids are commercially available under a wide variety of tradenames. Many of these are tabulated in Kirk-Othmer Encyclopedia ofChemical Technology, Volume 19, Second Edition, Interscience Publishers,New York. I969, pages 534 to 535 and pages 542 to 543.

The ashless surfactants of the present invention can also be made bycondensing the above-noted alkylene oxides with sulfonic acids.

The hydrocarbon sulfonic acids suitable for use as precursors to thealkoxylated sulfonic acids of this invention include oil solublepetroleum sulfonie acids and synthetic alkaryl sulfonic acids,particularly those having molecular weights of from about 200 to 500.These sulfonic acids can be produced by sulfonation of petroleum stocksor synthetic alkyl aromatic compounds, such as alkyl-substitutedbenzenes or napthalenes. wherein the alkyl groups attached to thearomatic ring contain at least about 8 carbon atoms, the wax-substitutedbenzenes and naphthalenes being par ticularly preferred.

The petroleum sulfonic acids, also known as sour oils, are thoseobtained in the treatment of petroleum oils. particularly refined orsemirefined oils. with concentrated or fuming sulfuric acid and whichremain in the oil after settling out of sludge. These sulfonic acids maybe represented by the general formula where R" is one or more alkyl,alkaryl or aralkyl groups, the aromatic nucleus is a single or condensedring or partially hydrogenated ring, and y is to 4.

The preferred alkoxylated sulfonic acids of this invention can becharacterized by the general formula:

wherein R is a C to C preferably C to C hydrocarbyl group, n" and m" areeach numbers between 0 and 16, the sum of n" m" is between about 6 andi6, and y is 0 to 4.

In the diesel fuels of the present invention, the abovedescribed ashlessdispersant and ashless surfactant are each used in the amount of about0.01 to about l.0 wt. preferably 0.02 to 0.2 wt. based on the crude oil.A light solvent oil is usually included with the additives to aidmixing. A typical solvent oil is a solvent extracted paraffinie oilhaving a distillation range of about 310 to 350F and a viscosity at 25Cof 0.779. Generally, heating is not required to effect solution in thesolvent oil.

The above-noted additives are combined with the crude oils generally bymixing them together with mild agitation and/or beating them to atemperature of 50 to l50F. preferably 75 to l00F for about 0.5 to 3.0hours. The dispersant and surfactant of the present invention are usedin to 0.! preferably i to 0.3, parts by weight of dispersant per part ofsurfactant by weight. The combination of dispersant and surfactant caneither be used to formulate a concentrate which is then added to thefuel or it can be added directly to form a fuel composition. If used ina concentrate. the combination of dispersanat and surfactant constitutes5 to I00 wt. of the concentrate. The remainder of the lit concentratecan be composed of an inert hydrocarbonsoluble diluent such as a lubeoil. diesel oil fraction or light solvent oil being in the range of 250to 400F. if added to a crude oil to form a diesel fuel. thedispersantsurfactant concentrate combination is added in the amount of0.01 to L0 parts by weight per hundred parts of oil.

EXAMPLES To demonstrate the effectiveness of the additive combination ofthe present invention, a series of comparative engine test runss weremade in a laboratory diesel engine. These tests involved the use of aBuda single cylinder diesel engine Model BD-38. Each test was carriedout for a period of 200 hours at an engine speed of about 1,500 rpm. Theinjector timing was set at l7.5 BTDC (before top dead center). the poweroutput was about 6 brake horsepower. the crankcase lubricating oiltemperature was maintained at about 240F.i2F.. and the water jackettemperature was maintained at about l90F.i2F. The exhaust gastemperature varied between about 800 and about 850F. The oil pressurewas at 33 pounds per square inch and the air intake pressure at about 3pounds per square inch.

The following additives. in the concentrations noted in the followingtable, were evaluated in crude oil according to the above-describedprocedure:

Additive A was a prior art. ash-containing additive, such as describedin US. Pat. No. 3.594.137. Specifically the additive was an overbasedbarium sulfonate derived from propylene-alkylated benzene sulfonic acidshaving a minimum total base number of 59 in a lubricating oilconcentrate (about to 48 wt. 71 active ingredient). About one-half ofthe total barium present was colloidal barium carbonate. The totalbarium content was between l4.3 and 14.9 wt.

Dispersant D-l. an ashless dispersant, was the con densation product of2.8 moles of polyisobutenyl succinic anhydride with 1 moleoftetraethylene pentamine in a lubricating oil concentrate containing70% of the active ingredient.

Surfactant S-l. an ethoxylated alkenylphenol. was a nonyl phenolethoxylated with an average of 6 to 9 moles of ethylene oxide and soldcommercially under the name of lgepal CO-530.

The crude oil used in these tests was the same as that described in US.Pat. No. 3.594.137 and had the following properties: API gravity at 60F.37.4; sulfur content. 0.26 wt. 7%; viscosity at l00F. 4i SUS; and saltcontent. 2.0 lbs/I000 bbls.

EFFECT OF ADDITIVES ON INJECTOR FOULlNG Dispersant D-l Additive in CrudeOil 507: Surfactant Sl Additive A Dispersant D-l Surfactant S-l Nil WI.1 additive (total) 0.05 0.l U.l 0.05 Crude Oil Consumption lbs/Z00 hr707 700 690 693 790 injector Fouling No. of injectors replaced 0 2 3 3 3Total carbon deposits On injectors and precombustion chamber. gm L030.48 2.33 2.38 .36 Used Oil Condition Vise inc i 32 44 46 I3 227 Pentaneinsol it 3.) 5.0 3.4 [.3 [3,4

Ash forming prior art components Comment Invention material of inventionbase oil The data in the first column of the table demonstrate that atotal of 0.05% of the dispersant-surfactant combination of the presentinvention reduces to zero the number of injectors which had to bereplaced because of fouling. In contrast, the second column shows thattwo injectors had to be replaced when using the ashforming additive ofthe U.S. Pat. No. 3,594,137, even though the concentration was twice asgreat. Although the carbon deposits with the ash-forming additive wereless, this is to be expected since twice as much additive was used. lnother respects the two formulations performed in a very similar fashion.

The data in the third and fourth columns show that neither thedispersant nor the ashless surfactant by itself in concentrationsequivalent to or greater than that of the first column led tosatisfactory results. In both these cases. three fuel injectors werefouled to the point requiring replacement.

Furthermore, a comparison of the data in the first column with those inthe third and fourth columns is clear evidence of the synergisticinteraction of the dispersant and surfactant in the formulations of thepresent invention. This invention formulation (first col umn) performedbetter than an equivalent amount of surfactant S-l or twice the amountof dispersant D-l What is claimed is:

I. An oil composition suitable for use as a fuel in a compression enginecomprised of a major amount of a synthetic or natural crude oilcontaining less than I wt. sulfur and less than 3.0 pounds of inorganicsalts per l000 barrels of oil, having an API gravity of about 25 to 45at 60F, a distillation boiling range of 160 to l IF and minor but enginedeposit reducing amounts of:

a. one or more ashless dispersants selected from the group consisting ofalkylene polyamine or polyol condensation products of: (i) alkenylsubstituted dicarboxylic acids or their anhydrides or (ii) alkenylsubstituted monocarboxylic acids or their anhydrides, said alkenyl groupcontaining between about 50 and 250 carbon atoms; and i b. one or moreashless, oil soluble surfactants selected from the group consisting of:(i) alkoxylated fatty acid esters of the general formula:

wherein R is a C to C aliphatic group, A is an oxygen or sulfur atom, nand m are each numbers from 0 to 14 and the sum of n m is between 2 tol4; (ii) an alkoxylated alkyl phenol of the general formula:

wherein A is as defined above, R is a C to C alkyl group, n and m areeach numbers from O to 14 and the sum ofn' m is between about 6 and I4;and (iii) alkoxylated sulfonic acids of the general formula:

wherein R" is a C to C hydrocarbyl group, n" and m" are each numbersbetween 0 and 16, the sum of n" m" is between about 6 and I6, and y is 0to 4.

2. An oil composition as claimed in claim 1 wherein said ashlessdispersant is a polyalkylene amine condensation product of saidall-tenyl substituted dicarboxylic acid or anhydride.

3. An oil composition as claimed in claim 2 wherein the ashlesssurfactant is said alkoxylated alkyl phenol or said alkoxylated fattyacid.

4. An oil composition as claimed in claim 1 wherein the ashlesssurfactant is said alkoxylated alkyl phenol or said alkoxylated fattyacid.

5. An oil composition as claimed in claim 1 wherein said crude oil is asynthetic crude oil derived from tar sands.

6. An oil composition as claimed in claim 1 wherein said ashlessdispersant is the condensation product of tetraethylene pentamine withisobutenyl succinic anhydride and said surfactant is said alkoxylatedphenol wherein n is between 6 and 9, m is 0 and R is between C5 to C10.

7. A process for running a heavy duty diesel engine having a fuelinjector which comprises running said engine while fueled with the crudeoil composition defined by elaim l.

1. AN OIL COMPOSITION SUITABLE FOR USE AS A FUEL IN A COMPRESSION ENGINECOMPRISED OF A MAJOR AMOUNT OF SYNTHETIC OR NATURAL CRUDE OIL CONTAININGLESS THAN 1 WT.% SULFUR AND LESS THAN 3.0 POUNDS OF INORGANIC SALTS PER1000 BARRELS OF OIL, HAVING AN API GRAVITY OF ABOUT 25* TO 45* AT 60*F,A DISTILLATION BOILING RANGE OF 160* TO 1100*F AND MINOR BUT ENGINEDEPOSIT REDUCING AMOUNTS OF: A. ONE OR MORE ASHLESS DISPERSANTS SELECTEDFROM THE GROUP CONSISTING OF ALKYLENE POLYAMINE OR POLYOL CONDENSATIONPRODUCTS OF: (I) ALKENYL SUBSTITUTED DICARBOXYLIC ACIDS OF THEIRANHYDRIDES OR (II) ALKENYL SUBSTITUTED MONOCARBOXYLIC ACIDS OR THEIRANHYDRIDES, SAID ALKENYL GROUP CONTAINING BETWEEN ABOUT 50 AND 250CARBON ATOMS; AND B. ONE OR MORE ASHLESS, OIL SOLUBLE SURFACTANTSSELECTED FROM THE GROUP CONSISTING OF: (I) ALKOXYLATED FATTY ACID ESTERSOF THE GENERAL FORMULA:
 2. An oil composition as claimed in claim 1wherein said ashless dispersant is a polyalkylene amine condensationproduct of said alkenyl substituted dicarboxylic acid or anhydride. 3.An oil composition as claimed in claim 2 wherein the ashless surfactantis said alkoxylated alkyl phenol or said alkoxylated fatty acid.
 4. Anoil composition as claimed in claim 1 wherein the ashless surfactant issaid alkoxylated alkyl phenol or said alkoxylated fatty acid.
 5. An oilcomposition as claimed in claim 1 wherein said crude oil is a syntheticcrude oil derived from tar sands.
 6. An oil composition as claimed inclaiM 1 wherein said ashless dispersant is the condensation product oftetraethylene pentamine with isobutenyl succinic anhydride and saidsurfactant is said alkoxylated phenol wherein n'' is between 6 and 9,m'' is 0 and R'' is between C6 to C10.
 7. A process for running a heavyduty diesel engine having a fuel injector which comprises running saidengine while fueled with the crude oil composition defined by claim 1.